Swift3 concurrency

轉自個人github: https://github.com/uniquejava/iOSConcurrencyDemo

swift3 concurrency

This repo is the steps breaking down from this excellent tutorial and an update for swift3 + xcode8. I seperated each step into its own commit, you can check the commit history for details.

The major difference is on GCD part, for NSOperation part, the changes are minor.

A compact example

Example from here qos - new quality of service syntax

weak self - to disrupt retain cycles

async global background queue - for network query

async main queue - for touching the UI.

Of course you need to add some error checking to this...

DispatchQueue.global(qos: .background).async { [weak self]
  () -> Void in
  self?.flickrPhoto.loadLargeImage {
      loadedFlickrPhoto, error in
      if error != nil {
          print("error:\(error)")
      } else {
      
          DispatchQueue.main.async {
              () -> Void in
              activityIndicator.removeFromSuperview()
              self?.imageView.image = self?.flickrPhoto.largeImage
          }
      }
  }
}

Swift2 GCD cheetsheet

get main queue

swift2 version:

dispatch_get_main_queue()

swift3 version:

DispatchQueue.main

global concurrent queue

swift2 version:

let queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)

swift3 version:

let queue = DispatchQueue.global(qos: .default)

custom serial queue

swift2 version:

let queue = dispatch_queue_create("com.cyper.xxx", DISPATCH_QUEUE_SERIAL)

swift3 version:

let queue = DispatchQueue(label: "com.cyper.xxx")

DispatchQueue by default is serial queue, you don't have to specify it in the initializer.

custom concurrent queue

swift2 version:

let queue = dispatch_queue_create("com.cyper.xxx", DISPATCH_QUEUE_CONCURRENT)

swift3 version:

let queue = DispatchQueue(label: "com.cyper.xxx", qos: .userInitiated, attributes: .concurrent)

NSOperationQueue

1. Removed the NS prefix
2. Simplified the method name
3. You can use xcode auto-fix

References

http://www.appcoda.com/ios-concurrency/

https://medium.com/swift-and-ios-writing/a-quick-look-at-gcd-and-swift-3-732bef6e1838#.ueryj2b2h

https://www.logcg.com/archives/2040.html

http://stackoverflow.com/questions/37805885/how-to-create-dispatch-queue-in-swift-3

Code

https://github.com/uniquejava/iOSConcurrencyDemo/blob/master/iOSConcurrencyDemo/ViewController.swift